In this simulation, students move a virtual compass around a bar magnet to predict the magnetic field for different locations around the magnet. Use the magnetic field meter to calculate strength of field as a function of distance. Next, click to superimpose Planet Earth over the bar magnet and see the surprising results in the orientation of the poles! (The Earth's magnetic north is located near the South Pole.) This model is designed to promote understanding of the Earth as a giant magnet that follows the rules governing magnetic fields. The compass needle points to magnetic north from whatever position it is located in the field. The simulation can be adapted well for use in middle school. For older students, the field meter allows for fairly accurate measurements of magnetic field strength measured in G.

Note to Users: As of 3/1/22 this simulation had not yet been converted to HTML5. The version available is a Ready-To-Run Java application by CheerpJ. It opens in Chrome, Edge, and Safari

This resource is part of a large collection of simulations developed by the Physics Education Technology project (PhET).

Please note that this resource requires at least version 1.5 of Java.